1. Field of the Invention
The present invention relates to a mechanically operated cartridge magazine for use with automatic weapons.
The history of weapon feed mechanisms include hand loading, internally and externally powered devices and the various combinations of round configurations and assembly. However, in regard to the present invention, i.e., a stored energy cylindrical drum feed mechanism for portable weapons, the availability of the devices is limited and of these limited devices, performance has been erratic and unreliable. F. A. Hobart on pages 22 and 23 of "Pictorial History of Submachine Guns" (Charles Scribner's Sons, New York, 1973) catalogued some of these weapons.
Maxim determined that a flat drum feed was impractical for sustained fire; Carr, with a high capacity drum, encountered power consumption difficulties; and the Lewis gun, with a flat rather than cylindrical disposition of the cartridge, was eminently successful as reported on pages 131, 226, and 280, respectively of "The Machine Gun", Vol. 1, McChin, George, Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.
U.S. patents which generally show the state of the art of drum magazines having approximately spiral internal configurations are as follows:
U.S. Pat. No. 290,622
U.S. Pat. No. 1,347,755
U.S. Pat. No. 1,361,402
U.S. Pat. No. 1,596,178
U.S. Pat. No. 2,394,606
U.S. Pat. No. 2,596,293
The problems with the prior art are explicitly spelled out in these patents, namely, the unevenness of drive pressure using a single rear-most arm on the cartridges, which also results in binding of the cartridges against the exterior guide walls, and the inability of spring mechanisms to exert sufficient pressure to accelerate and feed the cartridges within the time allowable during the excess breach block travel and the subsequent opening of the feeding aperture. Solutions of these problems have included using circular and non-spiral guide configurations, a second loading spring to bias the cartridge to the breach, and larger non-spring type of driving mechanisms. These solutions have not proved practical for the high speed weapons presently used.
Thus there exists the need for a drum cartridge magazine which resolves the problems of parasitic power consumption due to component loading manifested as friction between adjacent cartridges and between the cartridges and container, to provide reliable and high capacity, high speed cartridge feed.
2. Summary of the Invention
The present invention is a drum or cylindrical shaped cartridge magazine used with high speed weapons wherein a perfect spiral channel terminates in a tangentially linear exit section. A plurality of spider arms extending radially from a hub divide the cartridges into a plurality of groups of cartridges. An externally mounted torsion spring drives these spiders through the hub so as to bias and feed the cartridges from the spiral to the exit section. The spiral being a perfect Archimedian spiral defined by the equation r=K.theta.+a for the centerline of the channels on each opposing face of the housing. The walls of the channels differ or vary from the centerline by an amount defined by the radius of the nose and base of the cartridge respectively, such that the axis of the cartridge is parallel to the axis of the hub. The radial faces of the arms of the spider includes a plurality of indentures for engaging and driving the cartridges in the linear exit section. The radial distance of the indentures from the center of rotation increase radially by the diameter of the cartridge. The number of indentures in the radial face of an arm is one less than the number of cartridges in a group. Thus for four cartridges to a group, there are three indentures in the radial face of an arm. The lateral faces of the arms diverge radially so as to continuously engage the leading and trailing cartridge as the cartridge traverses the spiral channel by defining a constant circumferal distance between the lateral faces at all radial points.